JP3920575B2 - Channel information registration processing method in digital broadcast receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital broadcast receiver that receives digital TV broadcasts and digital audio broadcasts.
[0002]
[Prior art]
In a conventional television broadcast receiver, registration of channel information such as a receivable channel number and service information to the receiver is performed by executing a channel scan (search) for each channel. Conventionally, a search for acquiring channel information is executed for all channels including channels that are not actually broadcasted in order within a channel range that can be received by the tuner.
[0003]
By the way, in order to acquire the service information, it is necessary to wait until the demodulation / FEC circuit is locked. However, the demodulation / FEC circuit is not locked when a search is performed for a channel that is not actually being broadcast. Therefore, conventionally, it is determined whether or not the demodulation / FEC circuit is locked for a predetermined time, and if not locked, the search is shifted to the next channel. Thus, conventionally, since it is determined whether or not the demodulation / FEC circuit is locked even for a channel that is not actually broadcasted, there is a problem that it takes a very long time to register channel information. is there.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a digital broadcast receiver capable of shortening the channel information registration work time.
[0005]
[Means for Solving the Problems]
In the digital broadcast receiver according to the present invention, the channel information registration processing method sequentially selects a channel for each preset channel and outputs a signal indicating that the channel is normally received from the demodulation and forward error correction circuit. Preliminary scan that checks whether or not the received signal of each channel has a certain level of quality without deciding whether the channel number is higher than a certain level, and temporarily registers the channel number of the received signal as a receivable candidate in the storage device A first step for performing processing, and a signal indicating that reception has been performed normally from the demodulation and forward error correction circuit by sequentially selecting each receivable channel candidate temporarily registered in the storage device in the first step. There it is determined whether output, the second step of performing the scan process of registering to obtain the channel information needed by the signal is output Characterized in that it comprises.
[0006]
In the first step, the preliminary scan process may be performed a plurality of times.
[0007]
The preliminary scan process in the first step is preferably performed with the gain of the AGC amplifier in the tuner fixed.
[0008]
In the first step, whether or not the received signal has a certain quality or higher is determined based on, for example, whether or not the received power is greater than a predetermined value.
[0009]
The channel information includes, for example, a receivable channel number, service information in the case of a digital broadcast channel, and a distinction between a digital broadcast channel or an analog broadcast channel.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0011]
FIG. 1 shows the configuration of a digital broadcast receiver.
[0012]
In FIG. 1, 1 is a receiving antenna. Reference numeral 2 denotes a tuner that selects an RF signal from the antenna 1 and converts it into an intermediate frequency signal (IF signal).
[0013]
Reference numeral 3 denotes a first stage amplifier of the tuner 2. Reference numeral 4 denotes an AGC amplifier whose gain can be varied by an external control voltage. A down converter 5 converts the received RF signal into an IF signal that is a difference frequency between the local frequency signal generated by the voltage controlled oscillator 6 and the received RF signal. Reference numeral 7 denotes a PLL circuit which controls the frequency of the output signal of the voltage controlled oscillator 6 to a desired constant frequency based on the channel selection data from the CPU 21. A D / A converter 8 generates a gain control voltage of the AGC amplifier 4 based on control data from the CPU 21.
[0014]
9, 11 and 17 are intermediate frequency amplifiers. Reference numeral 10 denotes a band-pass filter that extracts an IF signal from the signal after frequency conversion (the output signal of the intermediate frequency amplifier 9). An A / D converter 12 converts the IF signal output from the intermediate frequency amplifier 11 into digital data. Reference numeral 13 denotes a demodulation / FEC circuit that demodulates the reception signal converted into digital data by the A / D converter 12 and performs error correction. Reference numeral 14 denotes an MPEG decoder that converts the transport stream in the MPEG format demodulated by the demodulation / FEC circuit 13 into a baseband signal.
[0015]
The demodulation / FEC circuit 13 outputs a lock signal (d) when the digital broadcast wave is normally received. Further, the demodulation / FEC circuit 13 has a function of determining whether or not the received broadcast wave is an analog broadcast wave based on whether or not the horizontal synchronization signal of the analog modulated wave has been extracted. The demodulation / FEC circuit 13 outputs an analog broadcast wave flag (c) when the analog broadcast wave is normally received.
[0016]
Reference numeral 15 denotes a baseband video signal output terminal. Reference numeral 16 denotes a baseband audio signal output terminal. Reference numeral 18 denotes a detection circuit that detects an IF signal output from the intermediate frequency amplifier 17. A comparator 19 compares the IF signal level after detection obtained by the detection circuit 18 with a reference voltage in order to determine whether or not the selected channel can be received. A D / A converter 20 generates a reference voltage for the comparator 19 by converting data from the CPU 21 into a voltage.
[0017]
21 is a CPU. Reference numeral 22 denotes a memory. An operation unit 23 is operated by a viewer. A remote control receiving unit 24 receives a signal from a remote controller (not shown) and sends a command to the operation unit 23. Reference numeral 25 denotes an SI decoder for demodulating service information multiplexed on each physical channel.
[0018]
FIG. 2 shows an example of the reception spectrum of the UHF-TV band.
[0019]
FIG. 3 shows a signal waveform (voltage waveform of the signal (a)) after detection when channel scanning is performed.
[0020]
FIG. 4 shows a signal indicating whether the selected channel is receivable, that is, an output signal of the comparator 19 (signal (b)).
[0021]
FIG. 5 shows a demodulated lock signal (signal (d)) indicating that the digital broadcast wave has been normally received and demodulated.
[0022]
FIG. 6 shows a flag indicating that the received signal is an analog broadcast wave, and is a waveform of the signal (c) output from the demodulation / FEC circuit 13.
[0023]
By the way, when an antenna or receiver is installed, or when the number of broadcast stations that can be newly received increases, the broadcast stations that can be received in the viewing area are checked in advance, and the viewer selects a receivable channel. In order to facilitate, it is necessary to register channel information such as receivable channels and service information in the receiver. When registering channel information, the viewer turns on the receiver and selects the channel scan mode from the initial menu on the operation unit 23.
[0024]
FIG. 7 shows a channel information registration processing procedure executed by the CPU 21 when the channel scan mode is selected.
[0025]
The channel information registration process includes a preliminary scan process and a main scan process. First, the preliminary scan process will be described.
[0026]
When the channel scan mode is selected, the CPU 21 sends data to the D / A converter 8 so that the gain of the AGC amplifier 4 is maximized (step 1). Further, the CPU 21 sends data to the D / A converter 20 in order to give the comparator 19 a reference voltage for determining whether or not the reception channel can be received (step 2).
[0027]
Further, the CPU 21 sets an initial value of the channel selection channel (step 3). As this initial value, the minimum value of the channel range is set, and in the case of domestic UHF, channel 13 is set as the initial value. Then, in order to select a channel number that has been set, channel selection data is sent to the PLL 7 (step 4).
[0028]
The radio wave received by the antenna 1 is amplified by the first stage amplifier 3 in the tuner 2, further amplified by the AGC amplifier 4 whose gain is set to the maximum value according to the instruction of the CPU 21, and then sent to the down converter 5. A local signal generated by the voltage controlled oscillator 6 is also sent to the down converter 5.
[0029]
The output signal of the down converter 5 is sent to the band-pass filter 10 through the amplifier 9. The band pass filter 10 outputs an IF signal of a desired reception channel. The IF signal is amplified by the amplifier 17 and then sent to the comparator 19 via the detection circuit 18. The comparator 19 compares the output voltage of the detection circuit 18 with the reference voltage output from the D / A converter 20 in order to determine whether or not the selected channel can be received.
[0030]
When the output voltage of the detection circuit 18 is larger than the reference voltage, the comparator 19 outputs an H level signal indicating that the selected channel can be received, and the output voltage of the detection circuit 18 is lower than the reference voltage. Sometimes, the comparator 19 outputs an L level signal indicating that the selected channel cannot be received. The CPU 21 determines whether or not the selected channel can be received based on the output of the comparator 19 (step 5).
[0031]
If the CPU 21 determines that the selected channel is receivable, it writes the channel number as a receivable channel candidate in the memory 22 (step 6), and then selects the selected channel number as the next channel number. (Step 7). On the other hand, if the CPU 21 determines that the selected channel is not receivable, the channel number is set to the next channel number without writing the channel number as a receivable channel candidate in the memory 22. Update (step 7).
[0032]
The CPU 21 determines whether or not the channel number updated in step 7 has exceeded the upper limit value (62 channels in this example) (step 8). If the channel number has not exceeded the upper limit value, the process returns to step 4 to perform similar processing. To do. If the channel number updated in step 7 exceeds the upper limit value, the preliminary scan process is terminated and the process proceeds to the main scan process.
[0033]
By the way, when a digital broadcast wave is received with a signal quality of a certain level or higher, the demodulation / FEC circuit 13 outputs a lock signal (signal (d) in FIG. 1) indicating that demodulation is possible. Determines whether the selected channel is receivable without checking the lock signal. In the preliminary scan process, the comparator 19 obtains a waveform as shown in FIG.
[0034]
Next, the main scanning process will be described.
[0035]
In the main scanning process, the CPU 21 releases the fixed gain of the AGC amplifier 4 (step 9). As a result, the gain of the AGC amplifier 4 is controlled to the optimum gain in accordance with the received signal level, as in normal reception.
[0036]
The CPU 21 reads one channel number from the channel numbers of the receivable channel candidates stored in the memory 22 by the preliminary scan process (step 10). 3 and 4, since channels 13, 15, 17, 18,..., 57, 59, 60, 62 are stored in the memory 22 as candidates for receivable channels, the channel 13 is read first.
[0037]
Then, the CPU 21 sends data to the PLL 7 in order to select the channel number read from the memory 22 (step 11). When the channel is selected, an IF signal corresponding to the selected channel is output from the tuner 2, converted into digital data by the A / D converter 12, and then sent to the demodulation / FEC circuit 13. Demodulation and error correction are performed.
[0038]
As described above, when the digital broadcast wave is normally received, the demodulation / FEC circuit 13 outputs the lock signal (d). When the analog broadcast wave is normally received, the analog broadcast wave flag (c) is output from the demodulation / FEC circuit 13.
[0039]
The CPU 21 determines whether or not the lock signal (d) is output from the demodulation / FEC circuit 13 (step 12), whether or not the analog broadcast wave flag (c) is output from the demodulation / FEC circuit 13 (step 13), and step 11 determines whether or not a predetermined time has passed since the channel selection was performed (step 14).
[0040]
When the CPU 21 receives the lock signal (d) from the demodulation / FEC circuit 13 (YES in step 12), the CPU 21 causes the SI decoder 25 to decode the service information from the demodulated data (step 15), and the decoded service information Is registered in the memory 22 as service information for the selected channel (step 16). Then, the process proceeds to step 18.
[0041]
When the CPU 21 receives the analog broadcast wave flag (c) from the demodulation / FEC circuit 13 (YES in step 13), the CPU 21 registers in the memory 22 that the selected channel is an analog broadcast channel. (Step 17). Then, the process proceeds to step 18.
[0042]
In addition, the CPU 21 receives neither the lock signal (d) nor the analog broadcast wave flag (c) from the demodulation / FEC circuit 13, and when a predetermined time has elapsed since the channel selection in step 11 is performed. Then, the process proceeds to step 18.
[0043]
In step 18, it is determined whether or not the processing from step 10 has been performed on all the receivable channel candidates in the memory 22. If the processing from step 10 onward is not performed for all the receivable channel candidates in the memory 22, the channel number is updated to the channel number of the next receivable channel candidate (step 19), and then to step 10. Return.
[0044]
When the processing from step 10 onward is performed for all the receivable channel candidates in the memory 22, the channel numbers of the receivable channel candidates stored in the memory 22 are deleted in the preliminary scan processing (step 20). ), The main scanning process is terminated.
[0045]
In the above embodiment, the preliminary scan process is performed only once, but the preliminary scan may be performed a plurality of times. If the preliminary scan is performed a plurality of times, even if the channel is determined to be a receivable channel candidate, it is a channel determined to be stably receivable, or the reception signal whose reception level changes with time due to fading or the like It becomes possible to determine whether the channel is of poor quality. Therefore, for a channel with poor received signal quality, the predetermined time in step 14 can be shortened during the main scanning process.
[0046]
【The invention's effect】
According to the present invention, the channel information registration work time can be shortened.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital broadcast receiver.
FIG. 2 is a time chart showing an example of a reception spectrum of a UHF-TV band.
FIG. 3 is a time chart showing signal waveforms after detection when channel scanning is performed.
FIG. 4 is a time chart showing a signal indicating whether or not a selected channel is receivable.
FIG. 5 is a time chart showing a demodulated lock signal indicating that a digital broadcast wave has been normally received and demodulated.
FIG. 6 is a time chart showing a flag indicating that the received signal is an analog broadcast wave.
FIG. 7 is a flowchart showing a channel information registration processing procedure.
[Explanation of symbols]
2 Tuner 13 Demodulation / FEC circuit 18 Detection circuit 19 Comparator 21 CPU
22 Memory 25 SI decoder

Claims (5)

Channel selection is performed sequentially for each preset channel, and the received signal of each channel is constant without determining whether or not a signal indicating normal reception from the demodulation and forward error correction circuit is output. The first step of checking whether or not the above quality is present and performing a preliminary scan process for temporarily registering a channel number having a received signal quality of a certain quality or higher as a receivable candidate in the storage device, and in the storage device in the first step Channel selection is performed sequentially for each tentatively registered receivable channel candidate to determine whether or not a signal indicating normal reception from the demodulation and forward error correction circuit is output, and the signal is output A second step of performing a main scan process for acquiring and registering necessary channel information when
A channel information registration processing method in a digital broadcast receiver.   2. The channel information registration processing method in a digital broadcast receiver according to claim 1, wherein the preliminary scanning process is performed a plurality of times in the first step.   3. The channel information registration processing method in the digital broadcast receiver according to claim 1, wherein the preliminary scan processing in the first step is performed in a state where the gain of the AGC amplifier in the tuner is fixed.   4. The digital broadcasting according to claim 1, wherein in the first step, whether or not the received signal has a certain quality is determined based on whether or not the received power is larger than a predetermined value. Channel information registration processing method in the receiver.   5. The digital broadcast according to claim 1, wherein the channel information includes a receivable channel number, service information in the case of a digital broadcast channel, and a distinction between a digital broadcast channel or an analog broadcast channel. Channel information registration processing method in the receiver.

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